algorithm - 如何找到二进制表示为回文的数字总数？

Question

找出二进制表示为回文的两个给定数字之间的数字总数的最佳方法是什么？ The problem I am trying to solve is here on spoj http://www.spoj.com/problems/BINPALI/

Answer 1

我解决了spoj问题，代码如下:

#include<iostream>
#include<algorithm>
#include<cctype>
#include<cstring>
#include<string>
using namespace std;
int main()
{
  int a,b,t;
  cin>>t;
  while(t--)
  {
     cin>>a>>b;
     int total=0;
     string s="";
     while(a<=b)
     {
       s="";
       for(int i=a;i>0;i=i/2)
       {
         if(i%2)
            s+='1';
         else
            s+='0';
       }
      string s2="",s3="";
      s2=s.substr(0,s.length()/2);
      int k=s.length();
      if(k%2)
        s3=s.substr(s.length()/2+1,s.length());
      else
        s3=s.substr(s.length()/2,s.length());
      reverse(s2.begin(),s2.end());
      if(s2==s3)
      {
         cout<<a<<" ";
         total++;
      }
      a++;
   }
if(!total)
    cout<<"none"<<endl;
}
return 0;
}